PROJECT SUMMARY/ABSTRACT Older adults are often victims of fraud, raising the question of whether age affects decision-making in such a way that makes people more susceptible to financial exploitation. One potential susceptibility is that older adults can have problems learning and acquiring information for later decision-making. However, significant gaps remain in our understanding of these potential deficits. Previous studies (1) have not examined learning in the social domain, which is most relevant for avoiding fraud; (2) have not examined multiple forms of learning, which may be differentially sensitive to age; and (3) have not examined whether deficits are a general function of age, or rather symptomatic of early pathological changes associated with preclinical Alzheimer's Disease or cerebrovascular disease, which can go undetected in otherwise cognitively normal older adults. This project will test older and middle-aged adults on two tasks using social stimuli that separately isolate hippocampal-mediated episodic learning, which encodes detail-rich associations between items and contexts from single events, and striatal-mediated stimulus-response learning, which encodes less flexible representations of a stimulus's value accrued over many events. Older adults will undergo a comprehensive clinical assessment and be determined to be cognitively normal as part of the Clinical Core longitudinal cohort of Penn's Alzheimer's Disease Core Center (ADCC). Age is expected to be associated with deficits in decisions based on both episodic memory and stimulus-response learning, though these deficits are expected to track with functional changes in different neural regions ? hippocampus and striatum, respectively ? as assessed with functional magnetic resonance imaging (MRI). As part of the ADCC, older adults will also receive positron emission tomography scans to assess amyloid pathology as well as MRI scans to assess white matter hyperintensity burden. Approximately 25% of cognitively normal adults show signs of either preclinical Alzheimer's Disease (amyloid pathology) or cerebrovascular disease (white matter hyperintensities). These data will be used to determine if social decision-making deficits are due to these previously undetected pathological changes, or to other brain structural changes that occur with healthy aging. Social decisions based on episodic memory may be particularly sensitive to preclinical Alzheimer's Disease, given that this targets the hippocampus, whereas social decisions based on stimulus-response learning may be particularly sensitive to cerebrovascular disease, given its impact on frontostriatal circuitry.